Esophagus

The esophagus is a hollow, muscular tube roughly 23 to 25 cm (about 10 inches) long that connects the pharynx (throat) to the stomach. It is the first long passage of the alimentary canal and serves a single primary job: moving the swallowed bolus of food and liquid downward into the stomach.

Structure and Location

Anatomists divide the esophagus into three parts. The short cervical portion begins in the neck just below the cricoid cartilage. The thoracic portion runs through the posterior mediastinum of the chest, passing behind the heart and trachea and to the left of the descending aorta. The brief abdominal portion passes through an opening in the diaphragm (the esophageal hiatus, near vertebra T10) and joins the stomach at the cardia.

A distinctive feature is its changing muscle composition: the upper third is mostly skeletal (voluntary) muscle, the middle third is mixed, and the lower two-thirds is smooth (involuntary) muscle. Two ring-like valves guard each end. The upper esophageal sphincter opens to admit food, and the lower esophageal sphincter (LES) opens to release food into the stomach while normally staying closed to block backflow.

Function

Swallowing triggers coordinated waves of muscle contraction called peristalsis that squeeze the bolus toward the stomach in seconds, even against gravity. The esophagus does not absorb nutrients; it is a conduit. The LES is critical because it acts as a one-way gate, keeping acidic stomach contents from washing back up.

Clinical Relevance

When the LES weakens or relaxes inappropriately, stomach acid refluxes upward, producing gastroesophageal reflux disease (GERD) and heartburn. Long-standing reflux can damage the lining and cause Barrett esophagus, a precancerous change that raises the risk of esophageal adenocarcinoma. Other conditions include achalasia, in which the LES fails to relax and swallowing becomes difficult, and esophageal cancers. Because the esophagus lies close to the airway, the heart, and major vessels, problems here can produce chest pain, swallowing difficulty (dysphagia), or regurgitation. This page is educational and is not a substitute for evaluation by a clinician.